Alpha-olefins have many uses. For example they are used to prepare polyethylene, polypropylene, and many or other polymeric plastic materials having a wide variety of uses. They are also useful in preparing many specialty chemicals. Typically alpha-olefins are produced from petroleum feed stocks. Alpha-olefins have an estimated market of at least 2.5 million tons per year.
Recently, L. J. Groor3en et al., Chem. Commun., 727 (2004) reported the decarboxylation of aliphatic carboxylic acids to yield α-olefins using the catalyst bis(2-diphenylphosphenophenyl)ether plus PdCl2 in polar solvents such as 1,3-dimethyltetrahydro-2(1H)-pyrimidinone in the presence of pivalic anhydride, at 110° C. In contrast to this complex system, J. A. Miller et al., J. Org. Chem., 58, 18 (1993) reported the conversion of (C10-C12)alkanoic acids in the presence of acetic anhydride or their symmetrical anhydrides, to the corresponding (Cn-1)1-alkenes at 250° C. in the presence of (Ph3)P2Pd(Cl2) with added Ph3P. At 250° C., 40 Torr, stearic acid and myristic acid were converted to 1-heptadecene and 1-tridecene at 250° C. Miller et al. also reported that the use of (Ph3P)4Pd plus Ph3P was much less efficient in the conversion of decanoic acid to 1-nonene in the presence of Ac2O, than was (Ph3)PdCl2 with added Ph3P.
However, there is a continuing need for methods to effectively convert a wide variety of organic carboxylic acids to the corresponding terminal and internal olefins, employing a variety of feed stocks. For example, there is a continuing need to find new non-petroleum based feed stocks from which they can be made, such as those generated from renewable resource feed stocks.
To improve the economic outlook of biodiesel and alkyl esters in general, the feedstock selection becomes critical. In particular, feeds containing high free fatty acid content, such as found in beef tallow or yellow grease, are significantly less expensive than vegetable oils, such as soybean, flaxseed or rapeseed oil. F. Ma et al., Ind. Eng. Chem., 37, 3768 (1998). These high free fatty acid feedstocks present significant processing problems in standard biodiesel manufacture since the free fatty acid is saponified by the homogeneous alkali catalyst that is used to transesterify triglycerides leading to a loss of catalyst as well as increased purification costs. See, e.g., D. G. B. Boocock et al., J. Amer. Oil. Chem. Soc., 75 1167 (1998).